Hittell was one of the most important authors on the subject of California history, writing (among other things);The Civil Practice Act of the State of California (1863)The Generals Laws of California (2 volumes) in 1865The Codes and Statutes of the State of California (2 volumes) in 1876 and 1880History of California (4 volumes) in 1885-1897A Brief History of California in 1898